MRK, Daiichi Begin Phase III Breast Cancer Study With ADC Candidate

Key Takeaways MRK and Daiichi start dosing in a phase III study of HER3-DXd in HR-positive, HER2-negative breast cancer.The study follows early data where HER3-DXd showed promising responses in metastatic breast cancer.Primary endpoints include progression-free and overall survival, with safety as a secondary measure.Merck (MRK) and Japan’s Daiichi Sankyo announced the dosing of the first patient in the phase III HERTHENA-Breast04 study evaluating their investigational HER3-directed DXd antibody-drug conjug ...